Symptoms of a drug allergy can range from mild itching and rash, to serious exfoliative dermatological conditions that can be life threatening. Symptoms can also include the respiratory system, to cause wheezing and trouble breathing, as well as cause anaphylaxis and anaphylactic shock.

In evaluating a patient with a suspected drug allergy, a detailed general medical history of the patient should be taken. Special attention should be given to taking a history of all prescription and non-prescription drugs taken, including; dates and dosages of all medications, drug formulations, routes of administration, clinical symptoms as well as their timing and duration in relation to exposure to the drug, and all previous drug exposures and reactions.

• Anaphylaxis, or severe allergic reaction (see below).
• Hives.
• Itching of the skin or eyes (common).
• Skin rash (common).
• Swelling of the lips, tongue, or face.
• Wheezing.

Symptoms of anaphylaxis include:

• Abdominal pain or cramping.
• Confusion.
• Diarrhea.
• Difficulty breathing with wheeze or hoarse voice.
• Dizziness.
• Fainting, lightheadedness.
• Hives over different parts of the body.
• Nausea, vomiting.
• Rapid pulse.
• Sensation of feeling the heart beat (palpitations).